ESP8266, Serial Adapters, and Resets

As detailed in the previous post, I’ve been having some trouble getting the Arduino development environment to automatically reset my ESP8266 board using the DTR and CTS lines of the serial adapter. Part of my problem may still have been the cheap serial adapter, but today I found a new part.

The ESP8266 is extremely sensitive to noise on the CH_PD line, and I was using a 9″ long jumper to connect CH_PD to RTS. I confirmed with my O-scope that RTS was pulsing as it should, but the first pulse threw the ESP8266 into some weird state where it spewed noise on a bunch of pins (GPIO0 seemed to be the worst), and uploading would, naturally, fail.

Switching to 3″ jumpers cleared up the problem and let my Arduino IDE reset the ESP8266 as it should.

I’ve changed the schematic in the Github repo for the project to reflect the new reset wiring, but I still have to add a 5V input connection for charging the battery. Once that’s done, I can design a new PCB.